Golf putter head

ABSTRACT

The present invention provides golf club heads exhibiting a relatively high moment of inertia. In certain embodiments, the present invention relates to golf putter heads comprising an aluminum inner core, which is capable of absorbing vibration, and an outer shell formed of another material, which is more dense and comprises less volume than the aluminum inner core. The material forming the outer shell may be polyurethane or nylon containing metallic powder.

BACKGROUND OF THE INVENTION

The present invention relates generally to golf clubs and, in particular, to golf putter heads.

Many golfers prefer to use putter heads which exhibit high moments of inertia. It has been found that such putter heads resist unwanted twisting movement during a putting stroke. Mallet putters have gained in popularity over the past several years, as many believe that mallet putters are easier to control. More particularly, many find that the relatively large size and weight of mallet putters are easier to swing over a desired path while minimizing such unwanted twisting movement about the vertical axis of such putter heads.

While some believe that the overall shape, size, and weight of mallet putters have, generally, provided golfers with putter heads that prevent unwanted twisting movement, there is still a need for improved mallet putter heads (and putter heads generally) which exhibit properties that discourage such twisting movement.

U.S. Pat. No. 3,387,844 to Shippee discloses a golf putter head having a hollow percussion chamber mounted in a recess forming a drum-like device with a resilient face for contacting golf balls. The club head may be formed of metal, and the percussion chamber may be formed of plastic or wood.

A golf putter head disclosed in U.S. Pat. No. 3,843,122 to Florian has a core structure containing a lightweight wooden block disposed between a pair of metal castings. The core structure is contained within a plastic shell, and a plastic insert is attached to one side of the shell to form a face for striking a golf ball.

U.S. Pat. No. 4,113,249 to Beery discloses a golf putter head including a front face with a vibratory cover plate mounted on the front face covering a recess formed in the front face. The vibratory cover plate is preferably formed of flexible and resilient material such as plastic so that it cooperates with the recess to provide a resonating chamber in the putter head.

A putter head disclosed in U.S. Pat. No. 4,156,526 to Huggins et al. has a block of resilient material pressed into a cavity defined by back, side and end walls of the putter head. The block has a striking surface, and it may be removed from the putter head to permit other blocks of different resiliency to be substituted therefor.

A putter head disclosed in U.S. Pat. No. 4,679,792 to Straza et al. is provided with a face insert formed of a honeycomb cellular structure that has individual cells filled by resilient material such as epoxy resin. Outer exposed ends of the resilient material form a striking face.

U.S. Pat. No. 5,083,778 to Douglass discloses a golf putter head having a rigid body and a resilient laminated face insert formed of inner and outer layers of resilient material. The inner layer of the face insert has a hardness which is less than that of the outer layer of the face insert. Preferably, the outer layer has a hardness which is equal to or greater than the hardness of a golf ball.

U.S. Pat. No. 5,458,332 to Fisher discloses a putter head with an elastomeric pad insert that is formulated to affect a reproducible direct linear relationship between the rebound factor of the pad insert and the distance from the putter head to an intended target.

U.S. Pat. No. 5,482,281 to Anderson discloses a golf putter head including a lower plate-like member made of heavyweight material, such as bronze or steel, and an upper shell-like member made of lightweight material, such as wood, aluminum, or plastic. A heel weight and a toe weight are mounted on the lower plate-like member adjacent to its heel and toe-ends, respectively.

A putter head disclosed in U.S. Pat. No. 5,485,997 to Schmidt et al. has a face plate insert formed of an elastomer, a synthetic resin or glass. The insert includes a medial portion that has a greater height than its opposite end portions.

U.S. Pat. No. 5,842,935 to Nelson discloses a golf putter head comprising a low density insert disposed in a cavity formed in a body. The insert has a front face arranged for impacting a golf ball. The volume of the insert is greater than the volume of the body, while the weight of the insert is less than the weight of the body.

SUMMARY OF THE INVENTION

The present invention provides a golf club head including an inner core formed of a first or lightweight material for absorbing vibration and an outer shell at least partially surrounding the inner core. The outer shell is formed of a second or heavyweight material which is more dense than the first material, and the outer shell has less volume than the inner core. Preferably, the first material forming the inner core is aluminum and the second material forming the outer shell is polyurethane or nylon containing metallic powder. In a preferred embodiment, the metallic powder is selected from a group of metallic powders consisting of tungsten powder, copper powder and steel powder.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom view of a golf putter head according to one embodiment of the present invention;

FIG. 2 is top view of the golf putter head shown in FIG. 1;

FIG. 3 is a back view of the golf putter head shown in FIG. 1;

FIG. 4 is a front view of the golf putter head shown in FIG. 1;

FIG. 5 is a toe-end view of the golf putter head shown in FIG. 1;

FIG. 6 is a heel-end view of the golf putter head shown in FIG. 1;

FIG. 7 is a vertical cross-sectional view of the golf putter head shown in FIG. 1; and

FIG. 8 is a vertical cross-sectional view of a golf putter head according to another embodiment of the present invention.

DESCRIPTION OF THE INVENTION

Referring to FIGS. 1-6, a golf putter head according to the present invention includes a heel end 10, a toe end 12, a bottom 14, a top 24, a back 16, and a front face 26. In the preferred embodiment, a shaft 38 is received in a bore 40 formed in the body heel end 10. In other embodiments, the bore 40 may be replaced by a hosel (not shown) which receives the shaft 38. The top 24 may include grooves or other markings 42 for use in aligning or aiming the putter head.

According to the present invention, the golf putter head includes an inner core 18 and an outer shell 20. The inner core 18 comprises a first material, preferably a lightweight or a low specific gravity material such as aluminum, that is capable of absorbing vibration that results upon striking a golf ball on the front face 26 of the putter head. The outer shell 20 is formed of a second material. Preferably, the second material is a heavyweight or a high specific gravity material in relation to the first material used to form the inner core 18. Accordingly, those skilled in the art will appreciate that the second material comprising the outer shell 20 will further exhibit a greater density in relation to the first material comprising the inner core 18.

The heavyweight material used to form the outer shell 20 is well known to those skilled in the art and, for example, may comprise polyurethane or nylon containing metallic powder. As already mentioned, this heavyweight material comprising the outer shell 20 preferably exhibits a higher specific gravity (or density) than the lightweight material comprising the inner core 18. Further, those skilled in the art will appreciate that a multitude of lightweight materials can be used to form the inner core 18 such as aluminum, elastomers, plastics, or any other material exhibiting the characteristics described herein.

In the preferred embodiment, the outer shell 20 comprises less volume than the inner core 18. The particular geometry that is employed to form the inner core 18 and outer shell 20 will vary depending on the attributes that are desired. For example, the inner core 18 may exhibit circular, oval, square, rectangular, or irregular geometries within the outer shell 20. The particular geometry used in a putter head according the present invention will depend on the desired distribution of mass within the putter head (as well as the desired total mass of the putter head).

The volume of outer shell 20 near the toe and heel ends 10, 12 of the putter heads (and corresponding volume of inner core material between such ends 10, 12) may be modified to achieve a desired moment of inertia. Also, the volume of outer shell 20 near the front face 26 and back 16 of the putter head (and corresponding inner core material between the putter head front face 26 and back 16) may also be adjusted to impart desired properties in the putter head. The specific geometries of the inner core 18 and outer shell 20 (in addition to the materials used to form them) are preferably configured to achieve a high moment of inertia which prevents unwanted twisting movement about the vertical axis 44 of the putter head.

In the preferred embodiment, the outer shell 20 is formed around the inner core 18 by injection molding so that the outer shell 20 at least partially surrounds the inner core 18 thereby partially concealing the inner core 18 within the outer shell 20. Injection molding is well known to those skilled in the art of golf club manufacturing and design.

The front surface 22 of the inner core 18 may be exposed and arranged for impacting a golf ball on the front face 26 of the putter head or, alternatively, it may be concealed within the front wall 28 of the outer shell 20. FIGS. 7 and 8 show putter heads wherein the front surface 22 of the inner core 22 is not exposed for impacting a golf ball but, rather, resides behind the front wall 28 of the outer shell 20. The inner core 18 may be contiguous with the top 24 or the bottom 26 of the putter head or it may reside entirely within with the outer shell 20. In a preferred embodiment, the bottom surface 30 of the inner core 18 is substantially contiguous with the bottom 14 of the putter head. In this embodiment, the bottom surface 30 of the inner core 18 is exposed as shown in FIGS. 1 and 7. In another embodiment, the top surface 32 of the inner core 18 is substantially contiguous with the top portion 24 of the putter head so that the top portion 32 of the inner core 18 is exposed as shown in FIG. 8.

While the putter head of the present invention may exhibit any of a plurality of geometries, configurations, designs, and mass distributions, putter head end portions 34 and 36 located adjacent the heel and toe ends 10 and 12, which are shown in FIG. 1, preferably, weigh more in the aggregate than the center portion 46 of the putter head. For example, depending on the material used to form the outer shell 20 and the inner core 18 (and the volume and geometry of the inner core 18 relative to the outer shell 20), it may be desirable that such end portions 34 and 36, in the aggregate, weigh more than the center portion 46 by a defined ratio.

More specifically, for example, if the end portions 34 and 36 each comprised a defined portion of the putter head, such as 25% of its length along the Y-axis shown in FIG. 2, such areas (in the aggregate) may comprise 1.25-1.50×, 1.50×-1.75×, 1.75×-2.00×, or greater than 2.00× the weight of the center portion 46. The foregoing weight distribution characteristics provide the putter head with a relatively high moment of inertia and natural resistance to unwanted twisting movement about its vertical axis 44 when moving in a direction along the X-axis. 

1. A golf club head comprising: an inner core formed of a first material for absorbing vibration; and an outer shell at least partially surrounding said inner core, said outer shell being formed of a second material which is more dense than said first material, said outer shell having less volume than said inner core.
 2. The golf club head of claim 1, wherein said first material is aluminum.
 3. The golf club head of claim 1, wherein said second material is polyurethane or nylon containing metallic powder.
 4. The golf club head of claim 3, wherein said metallic powder is selected from a group of metallic powders consisting of tungsten powder, copper powder and steel powder.
 5. The golf club head of claim 1, wherein said outer shell surrounds a majority of said inner core.
 6. The golf club head of claim 1, wherein a majority of said inner core is partially concealed within said outer shell.
 7. The golf club head of claim 1, wherein said inner core is partially exposed along one of a top and a bottom of the golf club head.
 8. The golf club head of claim 7, wherein said inner core is exposed along the top of the golf club head.
 9. The golf club head of claim 7, wherein said inner core is exposed along the bottom of the golf club head.
 10. A golf putter head comprising: an inner core formed of lightweight material for absorbing vibration; an outer shell formed of heavyweight material that is molded around said inner core so that said inner core is at least partially concealed within said outer shell, the heavyweight material being more dense than the lightweight material; and said outer shell having less volume than said inner core.
 11. The golf putter head of claim 10, wherein said lightweight material is aluminum.
 12. The golf putter head of claim 10, wherein said heavyweight material is polyurethane or nylon containing metallic powder.
 13. The golf putter head of claim 12, wherein said metallic powder is selected from a group of metallic powders consisting of tungsten powder, copper powder and steel powder.
 14. The golf putter head of claim 10, wherein said inner core is partially exposed along one of a top and a bottom of the golf club head.
 15. The golf putter head of claim 14, wherein said inner core is exposed along the top of the golf club head.
 16. The golf putter head of claim 14, wherein said inner core is exposed along the bottom of the golf club head.
 17. A method of making a golf club head comprising: providing an inner core formed of a first material; providing an outer shell formed of a second material which is more dense than said first material; and forming said outer shell so that it at least partially surrounds said inner core and has less volume than said inner core.
 18. The method of claim 17, wherein said first material is a lightweight material and wherein said second material is a heavyweight material.
 19. The method of claim 18, wherein said lightweight material is aluminum and wherein said heavyweight material is polyurethane or nylon containing metallic powder.
 20. The golf club head of claim 19, wherein said metallic powder is selected from a group of metallic powders consisting of tungsten powder, copper powder and steel powder. 